In a radio communication system, radio spectrums are the most important resources. Spectrums in existing networks are classified by the Radio Regulatory Commission according to different communication systems. Under such restrictions, many spectrum resources are not fully used. Communication rates of systems are restricted by their limited available spectrum bandwidths. Therefore, the Cognitive Radio (CR) system is proposed in existing technologies to make better use of radio spectrum resources.
Users in a CR system are usually classified into primary users and secondary users. A primary user owns radio spectrum resources. A secondary user can use spectrum holes in the channels of a primary user to send or receive data in the case that the communication of the primary user is not affected or that the impacts on the communication are within a specified threshold.
In a CR system, common channel state models include a discrete-time Markov model and a continuous-time Markov model. FIG. 1 shows a structural diagram of the discrete-time Markov model. The state transition probability of the discrete-time Markov model includes the probabilities of the state changing from 0 to 1 and from 1 to 0, which can be represented by α and β. FIG. 2 shows the continuous-time Markov model. The idle time of a channel is represented by X (X1, X2 . . . ) as shown in FIG. 2. The busy time of a channel is represented by Y (Y1, Y2 . . . ) as shown in FIG. 2. The idle time and busy time of a channel are exponentially distributed.
In the prior art, secondary users based on the Markov model need to estimate the channel usage of primary users and then select a channel according to the channel usage. That is, secondary users use the spectrum holes of channels of primary users to send or receive data. Take the discrete-time Markov model as an example. FIG. 3 shows a schematic diagram of the discrete-time Markov model and the channel usage of two primary users. For primary channel 1, time slots 2 and 4 are spectrum holes. For primary channel 2, time slots 1, 4, and 5 are spectrum holes. In this case, secondary users can use the preceding spectrum holes to send or receive data.
In the preceding solution in the prior art, the parameters of the Markov model are supposed to be known and constant. In actual application scenarios of the CR, multiple primary channels may be available for selection. Secondary users, however, may not know the channel parameters of the models used by the primary channels. In this case, the prior art may not select an optimum primary channel for access, thus affecting the system performance.